9. Common Stock

Early Exercise of Options for a Promissory Note

In December 2022, the Company’s former chief executive officer (the “Former CEO”), a then-related party, early exercised options for 349,321 shares of common stock in exchange for a partial recourse promissory note receivable with the principal amount of $1.1 million. The note bore interest at 4.27% per annum and was to be due in December 2027. For accounting purposes, the promissory note was determined to be non-recourse and, as such, the issuance of the promissory note and subsequent early exercise of stock options were considered not substantive.

On January 12, 2024, the Company and the Former CEO entered into a note forgiveness letter, pursuant to which the promissory note and all accrued interest thereon in an aggregate amount of $1.1 million were forgiven. As the shares subject to the options that were early exercised were vested as of the date of the forgiveness of the note, these are included in the calculation of net loss per share attributable to common stockholders from the date of the note’s forgiveness. The Company concluded that the note forgiveness was effectively a repricing of options and is a modification. Therefore, the incremental stock-based compensation expense was recognized for the vested shares at the modification date (see Note 10).

Shelf Registration Statement and the ATM Facility

On March 27, 2025, the Company filed a shelf registration statement on Form S-3 (the “Shelf Registration Statement”), covering the offer and sale from time to time of up to $250.0 million in aggregate offering price of shares of its common stock, shares of its preferred stock, debt securities, warrants, rights, units and/or depositary shares. The Shelf Registration Statement was declared effective by the SEC on April 15, 2025. The terms of any offering under the Shelf Registration Statement will be established at the time of such offering and will be described in a prospectus supplement to the Shelf Registration Statement filed with the SEC prior to the completion of any such offering.

The Shelf Registration Statement included a sales agreement prospectus covering the offer and sale from time to time through or to Jefferies, LLC (“Jefferies”), as sales agent, of up to $50.0 million in aggregate offering price of shares of the Company’s common stock under an Open Market Sale Agreement entered into with Jefferies on March 27, 2025 (the “ATM Facility”). In November 2025, the Company has sold 2,477,100 shares for net proceeds of $16.4 million after deducting the placement agent’s fees. As of December 31, 2025, $32.5 million of shares of common stock are available for sale under the ATM Facility.

December 2025 Offering

On December 17, 2025, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with the several underwriters named therein (the “Underwriters”), relating to the issuance and sale of an aggregate of 13,333,333 shares of the Company’s common stock at $7.50 per share under the Shelf Registration Statement. The offering closed on December 18, 2025. Pursuant to the Underwriting Agreement, the Underwriters were granted a 30-day option to purchase up to 1,999,999 additional shares (the “Option Shares”) of common stock, which was partially exercised and the underwriters purchased 704,499 shares of common stock on December 23,

2025. Total proceeds of the transaction, including the Option Shares were approximately $98.7 million, net of underwriting discounts and issuance costs.

As of December 31, 2025, $94.7 million remained available and unallocated under the Shelf Registration Statement.

Initial Public Offering

On February 7, 2024, the Company’s Registration Statement on Form S-1 for its IPO was declared effective, and on February 12, 2024, the Company closed the IPO and issued 16,675,000 shares of common stock at a price to the public of $22.00 per share, including 2,175,000 shares issued upon the exercise of underwriters’ option to purchase additional shares of common stock. The Company received gross proceeds of $366.9 million. Net proceeds were $336.2 million, after deducting underwriting commissions and other offering costs totaling $30.7 million. On February 8, 2024, the Company’s common stock began trading on the Nasdaq Global Select Market under the symbol “KYTX”. Immediately prior to the IPO closing, all of the outstanding shares of the Company’s redeemable convertible preferred stock converted into shares of the Company’s common stock on a 1-for-4.5511 basis.